Epson RC700, Руководство пользователя

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1. Introduction
4 RC700 / RC90 Option Fieldbus I/O Rev.14
Communication Types
There are two types of messaging connections: I/O messaging connection and Explicit
messaging connection. I/O messaging connection includes the four methods explained
below:
Polling : First, a master device sends output data to a slave device and then the
slave device responds. Data is normally exchanged in every
communication cycle. The communication frequency can be changed
by setting. This connection type is the most often used.
Strobe : First, a master device requests slave devices to send data with
multicast messages, and then, each slave device responds individually.
Data from many sensors on the system can be effectively gathered.
When the master does not receive responses from all requested slave
devices, a timeout error occurs.
Change Of State : A device sends data whenever it changes. Signals for device diagnosis
are sent regularly in the background. This connection type is useful for
remedying DeviceNet communication traffic.
Cyclic : A slave device transfers data regularly according to its internal timer.
This connection type is typically used for communicating with a
temperature controller.
The data transfer frequency is defined by master configuration.
For Change of State and Cyclic, the ACK which verifies communication completion
can be disabled by setting. However, never disable the ACK since communication
errors cannot be detected.
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NOTE